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fix(gatsby): quick check if string looks like a date #12700

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Mar 21, 2019
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fix(gatsby): quick check if string looks like a date #12700

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7 changes: 6 additions & 1 deletion packages/gatsby/src/schema/types/date.js
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Original file line number Diff line number Diff line change
Expand Up @@ -99,8 +99,13 @@ const GraphQLDate = new GraphQLScalarType({
// Check if this is a date.
// All the allowed ISO 8601 date-time formats used.
function isDate(value) {
// quick check if value does not look like a date
if (typeof value === `number` || !/^\d{4}/.test(value)) {
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I'm not sure an inline regex is the fastest way of determining if the first 4 values are numeric.

You could pre-compile, or alternatively even have a set of possible single digit strings, and iterate over the first 4 and break if it's not in the set.

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According to this benchmark, it seems inline regex or pre-compiled is actually fastest.

https://jsperf.com/check-whether-string-starts-with-four-numbers

In Chrome it doesn't appear to matter if it's inline or not, in Safari I notice a 2% improvement in pre-compiling.

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I tried both ways and the change was marginal, about 600s to build the schemas. Without the patch, it was 8000s. My guess is that the regex is optimized automatically.

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@wardpeet wardpeet Mar 21, 2019 •
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@me4502 I used string.slice(0, 4) and checked if it was a number and regex was faster. I'm pretty sure v8 optimizes for it. node is using v8 = chrome so we're probably good.

@millette at least we got somewhere, not fast enough but faster.

return false
}

const momentDate = moment.utc(value, ISO_8601_FORMAT, true)
return momentDate.isValid() && typeof value !== `number`
return momentDate.isValid()
}

const formatDate = ({
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